Transactional and lifecycle mail share a brand, so one bad campaign can degrade password-reset delivery.
What email A/B testing is#
A/B testing sends two or more variants of a message to random samples and measures which performs better on a chosen metric before sending the winner to the rest.
Why it matters#
Opinions about subject lines and layouts are unreliable; tests turn them into evidence and compound small gains over time.
Implementation plan for SaaS companies#
- Choose one variable per test and one primary metric (clicks or revenue, not opens).
- Size samples so results are statistically meaningful; small lists need bigger splits.
- Run long enough to capture late openers, typically 4 to 24 hours.
- Log results so learnings persist beyond one campaign.
Priorities specific to SaaS companies#
Transactional and lifecycle mail share a brand, so one bad campaign can degrade password-reset delivery. Weight your effort toward the steps above that address this constraint first, and measure with metrics that match how SaaS companies generate value from email.
Common mistakes#
- Testing several changes at once.
- Declaring winners on open rate after Mail Privacy Protection.
Frequently asked questions#
What should I A/B test first in email?
Subject lines, then the primary call to action, then send time. These have the largest measurable effect.